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LM7171: Stability

Spencer Siu
Prodigy 70 points
Part Number: LM7171

Hi, 

I am using the LM7171 in non-inverting configuration trying to amplify a sine wave as clean as possible. When implementing the circuit, there are a lot of peak frequencies in FFT analysis. Is there anyway to make the signal closer to a pure sine wave?

 

  • 0
    TI__Expert 8380 points

    Hi Spencer, 

    It certainly looks like you have an oscillation going on. Since you have plenty of gain, this is likely being caused by a pole created from the combination of the feedback resistor and input capacitance. The datasheet actually addresses this issue in section 7.5 and suggests adding a 2pF feedback capacitor to cancel out the pole. 

    Regards,